1. Field of the Invention
The present invention is related to a circuit for controlling sense amplifiers and, more particularly, to a circuit for controlling sense amplifiers which can operate a plurality of sense amplifier groups selectively.
2. Description of the Prior Arts
Generally, a sense amplifier in a semiconductor memory device is connected between a power supply voltage terminal Vcc and a ground voltage terminal Vss as shown in FIG. 1. And, a signal input terminal SENREF is connected to a bit line of a reference memory cell, and a signal input terminal SENDT is connected to a bit line of a selected memory cell.
When the sense amplifier enable signal is inputted through a signal input terminal SEb, the sense amplifier as described above compares the amount of current flowing through the bit line of the selected memory cell with the amount of current flowing through the bit line of the reference memory cell, and transfers the results to a data output buffer shown in FIG. 3 through an output terminal SAOUT.
Although, the sense amplifier plays a major role in reading data, the sense amplifier needs large amount of the power which occupies most of an entire power consumption of the device.
Meanwhile, the user can control freely the type of the data to be outputted such as 8 byte (x8), 16 byte (x16) etc. in the memory. Therefore, if a type of the data to be outputted is controlled to be 16 byte, it requires operation of sixteen (16) sense amplifiers and sixteen (16) data output buffers, if the type of the data to be outputted is controlled to be 8 byte, it requires operation of eight (8) sense amplifiers and eight (8) data output buffers. However, when the type of the data to be outputted is controlled to be 8 byte, eight (8) output buffers are only selected to operate, the 16 sense amplifiers are operated, thus unnecessary power are consumed. Moreover, as the memory device becomes higher integrated, an extremely small amount of current is flowed through the bit line of the memory cell, therefore, several stages of sense amplifiers must be constructed and a power consumption is more increased.